1. Field of the Invention
The present invention relates to an IC socket for electrically connecting an electronic package such as an integrated circuit (IC) with a circuit substrate such as a printed circuit board.
2. Description of Related Art
IC sockets are widely used for receiving and testing of IC packages in semiconductor industry. A conventional IC socket comprises a base mounted on a printed circuit board, and a lid movably engaged on the base. An IC package is assembled between the base and the lid to connect with the printed circuit board. Commonly, a plurality of coil springs is disposed between the base and the lid, abutting against the base and the lid and providing support therebetween. This kind of IC socket is shown in U.S. Pat. No. 6,341,970 to Han Shin Ho et al., dated Jan. 29, 2002.
Referring to FIGS. 5-6, a conventional IC socket is illustrated. The IC socket 6 comprises a base 61 mounted on a printed circuit board (not shown), a lid 62 movably mounted on the base 61, and a plurality of coil springs 63 disposed therebetween. The base 61 comprises a substantially rectangular configuration having four side walls, an engaging surface 610, and a mounting surface 612 for mounting an IC socket 64 to the printed circuit board. Each of the two opposite side walls of the base 61 defines a step 613 along an upper edge thereof. Each corner of the base 61 defines an assembly hole 614 having a bottom in the base 61 for accommodating a spring 63 therein, and one end of the spring 61 extends out of the engaging surface 610 of the base 61. The lid 62 comprises a plate 621 and four hooks 622 depending from two opposite edges of the plate 621, corresponding to the two steps 613.
In assembly, the lid 62 is pressed downwardly towards the base 61, and the lower surface of the lid 62 touches the top ends of the extending springs 63. When the lid 62 is mounted onto the base 61, the spring 63 is pressed, and the steps 613 of the base 61 engage with the four hooks 622 for preventing the lid 62 from departing from the base 61. Therefore, the springs 63 are sandwiched between the base 61 and the lid 62. In use, an IC chip 64 is disposed between the base 61 and lid 62. When the lid 62 is pressed downwardly, the IC chip 64 is clipped between the lid 62 and the base 61 for connecting with the PCB via the base 61.
However, one problem with this type of IC socket is that the compressed spring 63 between the lid 62 and the base 61 will inversely press the lid 62 when the lid 612 is mounted on the base. Therefore, the lid 62 may probably warp or distort under said pressure before it is pressed to clip the IC chip 64 onto the base 61, thereby affecting reliable mechanical and electrical characters of the IC socket.
In view of the above, a new IC socket with resistant mechanism which overcomes the above-mentioned disadvantages is desired.
Accordingly, an object of the present invention is to provide an IC socket with resistant mechanism for reducing the distortion of the lid under the pressure of the springs.
To achieve the above-mentioned object, an IC socket in accordance with a preferred embodiment of the present invention comprises a base mounted on a printed circuit board, a lid engaged onto the base, and a resistant mechanism disposed therebetween. The base comprises an engaging surface for supporting the IC chip and a mounting surface for connecting with the printed circuit board, a plurality of passageways is defined between the engaging surface and the mounting surface. Each corner of the base defines an assembly hole, and each assembly hole comprises a blocking surface near the mounting surface, a through hole extending from the blocking surface to the mounting surface of the base. The resistant mechanism comprises a pole with a first blocking member at one end thereof, a coil spring surrounding the pole, and a washer disposed between the first blocking member and corresponding end of the coil spring. The external diameter of the washer is bigger than the first blocking member. The lid comprises a plate and four hooks depending from two opposite edges of the plate, and the plate defines holes aligning with corresponding assembly hole of the base. The hole comprises a receiving hole for accommodating the first blocking member of the pole, and a circular step near to the bottom surface of the plate for pressing the washer. That is, the diameter of the receiving hole is bigger than the external diameter of the first blocking member, and smaller than the diameter of the circular step.
In assembly, the pole extends through the washer and the coil spring in sequence. The pole with the surrounding coil spring inserts into the assembly hole of the base, and one end of the coil spring bears against the blocking surface of the assembly hole. The inserted end of the pole extends through the through hole and locates in the recess of the mounting surface to engage with the second member. Therefore, the coil spring is restricted between the washer and the blocking surface of the assembly hole.
The lid is pressed downwardly towards the base, and the hooks deflect outwardly as they ride over the steps of the base. The lid is attached onto the base by the loose engagement of the hooks and the steps, with the first blocking member of the pole fittingly inserted into the receiving hole, and the washer loosely depending on the circular step. Therefore, the spring will not perform extra pressure to the lid besides supporting the weight thereof before the lid is pressed downwardly to clip the IC chip on the base, and the distortion of the lid is effectively reduced.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: